Non-League football is football in England played at a level below that of the Premier League and the three divisions of The Football League. The term non-League was commonly used well before 1992 when the top football clubs in England all belonged to The Football League; all clubs who were not a part of The Football League were therefore non-League clubs.

The "League" of "non-League football" refers to the Football League, rather than leagues in general – "non-League" clubs play most of their football in league competitions. There are many leagues below the level of The Football League, and some, such as the Northern League, are almost as old as the League itself. The most senior of these leagues are loosely organised by The Football Association, the sport's governing body in England, into a National League System (NLS). The NLS has seven levels or steps, and includes over 50 separate leagues, many with more than one division.

Prior to 1987 there was no automatic promotion and relegation between The Football League and the leagues of non-League football. The bottom clubs of The Football League were required to apply for re-election to the League at the end of the season, but this was in most cases a mere formality. The system ensured that Football League membership remained relatively static, with non-League clubs having almost no chance of joining.

However major change came in 1987 when automatic promotion and relegation of one club between The Football League and The Football Conference, the top league in non-League football, was introduced, subject to the eligible club meeting the required facility and financial standards. Scarborough became the first non-League club to win automatic promotion to The Football League, and Lincoln City became the first League club to be relegated to the ranks of non-League football. Since 2003 two clubs from the Conference (the champions and the winners of a playoff) have been promoted at the end of each season.

The entire English football league system includes the Premier League, The Football League, the NLS leagues, and any local leagues that have feeder relationships with an NLS league.

Many non-league clubs enter the FA Cup, where they hope to become "giant-killers" by progressing from the qualifying rounds, and first and second rounds proper, to meet and beat opposition from the Premier League or Football LeagueChampionship. Since the end of the Second World War, seven non-league clubs have reached the Fifth Round of the FA Cup. The only non-League team to have won the competition since the Football League started is Tottenham Hotspur in the 1901 FA Cup Final, although at the time the Football League consisted almost entirely of northern clubs, and the leading non-League clubs in the south were of a comparable standard to the League clubs.

The Football Association Challenge Trophy was formed in 1970 by the FA to offer non-league football clubs a realistic chance of winning a cup competition. Now in its 43rd season (2011–12), it is becoming more and more popular for non-league fans around the country.[citation needed] There is also the FA Vase for clubs further down the league ladder.

In Scotland, football outside the top four divisions consists of the Junior leagues together with a number of regional Senior Leagues, although the term non-League is also commonly used. It is also used throughout Europe, although in Germany non-professional leagues are known as Regionalliga, as the leagues are all regional depending on the location of the town or city the team represents, unlike 1. Bundesliga, 2. Bundesliga and 3. Liga all being national leagues. Until 1974, it was the second tier of the league system before being disbanded. The Regionalliga was then re-introduced as the third tier of the system in 1994. Upon introduction of the 3. Liga in 2008, it was demoted to the fourth level of the pyramid, in the same way every league below the 5th step of the English pyramid was moved a step down due to the introduction of the Conference North and South.

In the Republic of Ireland, football outside the top two divisions consists of regional Senior Leagues based on which Province the club comes from; although once again these leagues are commonly referred to as 'Non-League'.